Control device for driers



1965 T. R. SMITH 3,197,885

CONTROL DEVICE FOR DRIERS F'iled Jan. 11, 1963 2 Sheets-Sheet l IN V EN TOR.

7720772061? find/L, B

Aug. 3, 1965 T. R. SMITH CONTROL DEVICE FOR DRIERS 2 Sheets-Sheet 2 Filed Jan. 11, 1963 INVENTQR. 520772061? find/z, mi A GEN T United States Patent 3,l97,$l35 CQNTEQL DEVKCE FQR DEERE; Thomas R. Smith, Newton, lows, assignor to The Maytag t'lomuany, Newton, lowa, a corporation of Delaware nine .la n, 1963, Ser. No. seams in (Jlaims. or. se -4e This application is a continuation of application of Thomas R. Smith Serial N0. 40,663 filed July I), l9 60, now abandoned, and a continuation-in-part of application of Thomas R. Smith Serial No. 22,323 filed April 14, 1960, now abandoned, assigned to the same assignee as the present invention.

This invention relates to devices for directly determining the condition of fabrics employed in a control system of a machine for drying fabrics, and more particularly, to electrodes for contacting and completing an electrical circuit through fabrics.

Many attempts have been made to control the ternnnation point of drying operations as related, directly, or indirectly, to the condition of the fabrics. Elberty Patent No. 2,045,381, for example, relies upon the change in conductivity of the fabrics as the moisture is removed in order to discontinue operation of a drying machine at the moment electrical conductivity of the fabrics, as sensed directly between conductors in the drum, attains a predetermined Value.

In other control systems, the humidity of the air within the drier is measured to determine when the drying operation should be terminated, instead of direct measurements of the electrical conductivity of the fabrics, illustrated in Horecky Patent No. 2,820,304, for example. Humidity determinations are an unreliable index of the condition of the fabrics, and control systems dependent thereon contain an inherent deficiency.

In still other systems attempts have been made to control the termination of the drying period by thermostats in the drier. In these systems the thermostats operate to shut-off the heaters when the temperature within the drying cabinet rises above a set value which occurs when most of the clothes have been dried. Again, the control does not insure that all of the fabrics have been dried.

It is an object of the present invention to provide a control system for a clothes drier responsive to the dry condition of the fabrics being treated. It is a further object of the invention to provide a system for controlling termination of a drying operation that is responsive to the direct determination of the electrical conductivity of the fabrics, so as to obtain reliable shut-elf of the drying operation. It is a still further ob ect of the invention to provide a system whereby direct response of the control to the dryness or conductivity of fabrics is made practical or easible for home laundry clothes driers. Further objects and advantages of this invention will become evident as the description proceeds and from an examination of the accompanying drawings which illustrate several embodiments of the invention and in which similar numerals refer to similar parts throughout the several views.

in the drawings:

FIGURE 1 is a view in vertical section, partly broken away showing a drier which incorporates the control system of the invention;

FIGURE 2 is an enlarged view in lon itudinal section of one of the baffles in the drum, illustrating the arrangement of electrodes thereon;

FIGURE 3 is a bottom View of the baffle shown in FIGURE 2;

FIGURE 4 is an enlarged View of the surface of the baffle of FIGURE 2 showing the location of the conductors; and I FIGURE 5 is a fragmentary View partly in section of a modified form of bafile.

Briefly described, the invention relates to a control systern in which conductors, electrodes, or probes, directly contact fabrics being dried to directly determine their electrical conductivity. The conductors, electrodes, or probes are mounted in the baflles of the revoluble drum which tumbles the fabrics and positioned to prevent electrical shorting by metallic articles which might be fastened to the fabrics.

Referring now to the drawings, FIGURE 1 showns a clothes drier having a base frame 10 which serves as a support for upstanding channel base members 11 and 12 which together with cross piece 14 support the hollow blower housing casting 17. Housing 17 includes a tubular portion 21, a divider wall 2% having a rearwardly flared inner portion defining an intake into an impeller chamber,

and radially directed longitudinal webs 22 which converge toward each other to provide a retainer member 23. A passageway 26 is located between the tubular portion 21 and the bearing retainer member 23 which trausverses the supporting webs 22.

Within member 23 is journalled a revoluble drum drive shaft 31 which projects from both ends of the housing 17. Afiixed to drum drive shaft 31 at the rear of the cabinet is a large pulley 33 which is driven by motor 34 through motor pulley 36, main drive belt 37, a speed reduction system (not shown) and belt 4t).

The opposite or forward end of the drum drive shaft 31 is rigidly connected to the drum spider member 46 which has radiating spokes 51 that support rim 52. A heat resistant sealing member 54 encircles the front periphery of blower housing 17 and the circular shoulder 55 located on the rear portion of drum spider 46.

A horizontally mounted tumbling drum has a rear wall 61 which is secured to rim 52 for support and rotation by shaft 31. Rear drum wall 61 is imperforate except for a central exhaust opening 62.

The periphery of rear wall 61 is flanged to form a supporting shoulder for the imperforate cylindrical side wall as which carries the clothes elevating vanes 66 for turnbling clothing Within drum 6% during rotation of the latter member. Cylindrical side Wall is connected to the front drum wall 67.

Front wall 67 has a centrally located access opening 63 and a circular perforate portion 69 located concentrically to access opening 68. This perforate portion (29, formed by several concentric rows of holes, serves as the air intake into drum 69.

The cabinet 70 which is fastened to base frame 10 and which encloses the entire drying mechanism has an access opening 71 aligned to drum access opening 68 thereby allowing both of openings 68 and 71 to receive the door gasket 72 of door 73. The door 73 is hinged to form an airtight seal for cabinet 7%.

Fastened to cabinet 74 is the shroud or cowling member 74. Located between shroud 74- and the front drum wall 67 is an open coil electric heating element 75 which extends completely around the inside of cowling member 74 to raise the temperature of air passing through perforate portion 69 in the front drum wall 67. It will be understood that a gas heater may be used in place of the electrical element.

Air flow into drum 60 through the perforate area 69 and into the blower housing 17 is produced by rotation of the revoluble impeller member 76 located in blower housing 17. Fan pulley 77 is connected to the driving motor 34 by main drive belt 37. The blower housing casting 17 supports a cycling thermostat 78 which is connected in series with the heating element 75 in order to maintain the interior of drum 60 at the proper selected drying temperature.

In order to measure the electrical conductivity or resistance for determining the condition of dryness of the r. fabrics, electrodes or probes 8%, 81 are mounted within the drum 60. In the form shown, a pair of electrodes of opposite polarity are spirally wound about each of the drum baffles 66 to provide a maximum amount of contracting or probing surfaces exposed to the fabrics placed within the drum. As best illustrated in FIGURE 2, the electrodes are preferably set in recesses or grooves in the baffles containing therebetween outwardly projecting shoulders, or ridges, 95 to prevent shorting therebetween by metallic objects sometimes attached to the fabrics, for example, metal buttons, clips, buckles, and the Electrical energy is supplied to electrode 80 by lead 84 that is connected to brush 85 which engages the stationary slip ring 86 while the drum 6% is rotating. The slip ring 86 may be supported on an electrically insulative band 87 mounted on housing 117. Slip ring 86 is in turn connected to a lead 90 which runs to the control unit 92. Electrode 81 may also be supplied with electrical energy of the opposite polarity to electrode 86 by similar arrangement of brushes and slip rings. It is preferred, however, to ground electrode 81 to the rotatable drum 60, so that it is supplied by current from lead 91 which is also grounded to the framework of the drier.

The automatic control unit 92 may be secured to the upper portion of the cabinet. Leads 90, 91 enter the control unit and are connected to the control circuit 92 as more fully described in copending application of Thomas R. Smith, Serial No. 22,323.

Baflles 66 are formed of electrically non-conductive material in order to insulate the electrodes. However, the electrodes are electrically shorted by contacting the wet fabrics during tumbling. Ordinarily, a plurality of bafiies 66 are mounted within the drum 60, each of which is provided with electrodes $0, 81, and the respective electrodes of all the baflles connected in parallel although a single baffle provided with electrodes may be used.

Referring now to FIGURES 2 through 4, which illustrate the balfies in detail, the wire electrodes 80, 81 are spirally wound on the surface of the baffles; the ends 96, 97 being secured to the bottom interior of the baffles by suitable insulators. The leads 83, 84 from the electrodes are electrically connected to the control system and are preferably insulated. To further insure minimum current leakage from electrodes 8t), 81, insulation may be advantageously provided on the entire electrode except in the area of fabric contact, namely, the crown area 93 of the baffles. In the crown area 93, the electrodes are bare to permit electrical shorting by wet fabrics during tn 1.- bling.

The baffles may be formed of synthetic resinous materials so as to be electrically insulative, and may be hollow. The shoulders, or ridges 95 are molded into the surface. Screw sockets 99 are formed in the base of the baffles for mounting to the interior surface of the drum.

Since the electrodes contact the fabrics for determining fabric electrical conductivity, shorting of the electrodes by metallic objects is, of course, undesirable. By positioning shoulders, or ridges 95, however, between adjacent electrodes of a height greater than the outer diameter of the electrodes, simultaneous contact by flat metallic objects of adjacent electrodes is avoided. Thus, fabrics because of their limp, flexible nature, drape over the shoulders, or ridges 95 to complete an electrical circuit through the electrodes. On the other hand, metallic objects because of their inherent rigidity, are prevented from contacting adjacent electrode pairs by the shoulders, or ridges 95. The result is selective determination of fabric electrical resistance.

Referring now to the modified form of FIGURE 5, the electrodes 30', 81' are wound on the smooth surface of the baffles 66'. The ridges 95 between adjacent electrodes are formed by wrapping a strip of insulative mate- .rial between each pair 91 adjacent electrodes. The ind sulative strip is of a depth greater than the outer diameter of the electrodes, so that the electrodes are recessed below the outer surface of the insulative strip.

In the drawings and specification therehave been set forth several embodiments of the invention, and although specific terms are empioycd, these are used in a generic and descriptive sense only, and not for purposes of limitation. Changes in form and the proportion of parts, as well as the substitution of equivalents are contemplated, as circumstances may suggest or render expedient, without department from the spirit or scope of this invention as further defined in the following claims.

I claim:

1. In an apparatus for drying fabrics, a revoluble drum for drying fabrics, means for rotating said drum to tumble the fabrics, heating means for drying fabrics in said drum, at least one bafile member mounted on the interior surface of said drum for engaging the fabrics, at least one pair of elongated, narrow electrodes positioned within said drum for contact by the fabrics, circuit means connected to said electrodes for controlling the apparatus, and at least one electrically insulative ridge means projecting between and beyond said pair of electrodes for selectively permitting shorting by the fabrics and preventing shorting by rigid metallic objects across said pair of elongated electrodes.

2. In an apparatus for drying fabrics, at revoluble drum for drying fabrics, means for rotating said drum to tumble the fabrics, heating means for drying fabrics in said drum, at least one baffle member mounted on the interior surface of said drum for engaging the fabrics, said baffle member formed of electrically insulative material, at least one pair of elongated, narrow electrodes positioned on said bafiie member for contact by the fabrics, circuit means connected to said electrodes for controlling the apparatus, and electrically insulative shoulder means separating and extending beyond adjacent electrodes for selective bridging and contacting of said pair of electrodes by fabrics and for preventing bridging and contacting of said pair of electrodes by rigid metallic objects.

3. In an apparatus for drying fabrics, a revoluble drum for drying fabrics, means for rotating said drum to tumble the fabrics, heating means for drying fabrics in said drum, at least one baffle member mounted on the interior surface of said drum for engaging the fabrics, at least one pair of electrodes positioned in elongated parallel rows on said baffle member for contact by the fabrics circuit means connected to said electrode for controlling the apparatus, and an electrically insulative ridge means on said baflie projecting between and beyond said pair of electrodes a distance greater than the thickness of said electrodes.

4. In a drier having a control system for terminating the drying operation, a revoluble drum for drying fabrics, means for rotating said drum to tumble the fabrics, heating means for drying fabrics in said drum, batfie members mounted on the interior surface of said drum for engaging the fabrics, at least one of said baffle members formed of electrically insulative materials, at least one pair of electrodes juxtaposed on said baiile member in elongated, narrow rows for contact by the fabrics, and electrically insulative shoulder means projecting outwardly between circuit means for connecting said electrodes to the control system, and beyond the thickness of said electrodes.

5. In an apparatus for drying fabrics, a revoluble drum for drying fabrics, means for rotating said drum to tumble the fabrics, heating means for drying fabrics in said drum, electrode means in said drum openly facing the interior thereof for contact by said fabrics, said electrode means including at least two conductive elements electrically insulated from each other, circuit means connected to said electrodes for controlling the apparatus, and electrically insulative means projecting from between said conductive elements a distance sufficient for preventing flat metallic objects forming electrical connection there between.

6. In an apparatus for drying fabrics, a revoluble drum for drying fabrics, means for rotating said drum to tumble the fabrics, heating means for drying fabrics in said drum, means including at least one baffle member mounted on the interior of said drum for engaging the fabrics, means including at least one pair of electrodes positioned in said drum openly facing the interior thereof for contact by the fabrics, circuit means connected to said elec trodes for controlling the apparatus and electrically insulative shoulder means extending from between said pair of electrodes and beyond at least one electrode thereof a distance sufficient to substantially prevent shorting by fiat rigid metallic objects usually associated with the fabrics.

7. In a drier having an electrical control system for termination of the drying operation, a revoluble drum for drying fabrics, means for rotating said drum to tumble the fabrics, heating means for drying fabrics in said drum, means including at least one baflle member mounted inside said drum for engaging the fabrics, a plurality of electrode pairs positioned on said bafile member openly facing the interior of said drum for contact by the fabrics, each of said electrode pairs juxtaposed in elongated narroW rows, said electrode pairs connected in electrical parallel to circuit means in the electrical control system for said drier, and electrically insulative means extending between and beyond at least one electrode of each of said electrode pairs an amount suflicient for preventing electrical shorting across said electrode pairs by fiat rnetallic articles.

8. In a drier having an electrical control system for termination of the drying operation, a revoluble drum for drying fabrics, means for rotating said drum to tumble the fabrics, heating means for drying fabrics in said drum, means including at least one pair of electrically conductive elements positioned in said drum openly facing the interior thereof for contact by the fabrics, means for supplying electrical current to said elements, at least one baffle means mounted inside said drum for engaging the fabrics, said bafile means having at least one of said elements positioned on said baflle means, and electrically insulative means extending between said elements and beyond at least one thereof for selectively permitting shorting of said elements by the fabrics and substantially pre venting shorting of said elements by relatively fiat metallic surfaces.

9. In a drier having an electrical control system for termination of the drying operation, a revoluble drum for drying fabrics, means for rotating said drum to tumble the fabrics, heating means for drying fabrics in said drum, means including at least one bafile member mounted inside said drum for engaging the fabrics, means including at least one electrode pair associated with said baffle member and openly facing the interior of said drum for contact by the fabrics, and electrically insulative means positioned between said electrode pair and including a shoulder extending beyond at least one electrode thereof an amount sufiicient for preventing electrical shorting across said electrode pair by relatively fiat metallic surfaces.

141. In a drier having an electrical control system for termination of the drying operation, a revoluble drum for drying fabrics, means for rotating said drum to tumble the fabrics, heating means for drying fabrics in said drum, means including at least one electrode pair positioned in said drum for contact by the fabrics, and electrically insulative ridge means projecting from between said electrode pair and extending beyond at least one electrode thereof for selectively permitting shorting of said electrode pair by the fabrics and substantially preventing shorting of said electrode pair by relatively flat rigid metallic surfaces.

References Cited by the Examiner UNITED STATES PATENTS 2,045,381 6/36 Elberty 324 X 2,653,298 9/53 McKinley 324-65 X 2,852,740 9/58 Posey.

2,991,641 7/61 Woodling 3445 X 3,073,161 1/63 Crabtree 338-35 X 3,105,214 9/63 Blythe 338-65 NORMAN YUDKOFF, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,197,885 August 3, 1965 Thomas R. Smith It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line 5, for "contracting" read contacting column 4, lines 62 and 63, strike out "circuit means for connecting said electrodes to the control system," and insert the same after "fabrics," in line 60, same column 4.

Signed and sealed this 15th day of February 1966.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. IN AN APPARATUS FOR DRYING FABRICS, A REVOLUBLE DRUM FOR DRYING FABRICS, MEANS FOR ROTATING SAID DRUM TO TUMBLE THE FABRICS, HEATING MEANS FOR DRYING FABRICS IN SAID DRUM, AT LEAST ONE BAFFLE MEMBER MOUNTED ON THE INTERIOR SURFACE OF SAID DRUM FOR ENGAGING THE FABRICS, AT LEAST ONE PAIR OF ELONGATED, NARROW ELECTRODES POSITIONED WITHIN SAID DRUM FOR CONTACT BY THE FABRICS, CIRCUIT MEANS CONNECTED TO SAID ELECTRODES FOR CONTROLLING THE APPARATUS, AND AT LEAST ONE ELECTRICALLY INSULATIVE RIDGE MEANS PROJECTING BETWEEN AND BEYOND SAID PAIR OF ELECTRODES FOR SELECTIVELY PERMITTING SHORTING BY THE FABRICS AND PREVENTING SHORTING BY RIGID METALLIC OBJECTS ACROSS SAID PAIR OF ELONGATED ELECTRODES. 